Androgen and estrogen, which are sex hormones, show a great diversity of physiological activities inclusive of differentiation and proliferation of cells. On the other hand, it has been clarified that androgen and estrogen act as an exacerbation factor in certain diseases. It is known that steroid C17, 20-lyase is responsible for the final stage of the biosynthesis of androgen in the body. That is, steroid C17,20-lyase produces dehydroepiandrosterone and androstenedione using, as a substrate, 17-hydroxypregnenolone and 17-hydroxyprogesterone, which are generated by cholesterol. Therefore, a pharmaceutical agent inhibiting steroid C17,20-lyase suppresses production of androgen, as well as production of estrogen synthesized using androgen as a substrate. Such pharmaceutical agent is useful as an agent for the prevention and therapy of diseases wherein androgen and estrogen are exacerbation factors. Examples of the diseases, in which androgen or estrogen is an exacerbation factor, include prostate cancer, prostatic hypertrophy, masculinism, hypertrichosis, male-type baldness, male infant-type prematurity, breast cancer, uterine cancer, ovarian cancer, mastopathy, hysteromyoma, endometriosis, adenomyosis of uterus, polycystic ovary syndrome and the like.
Steroid-type compounds and non-steroid type compounds are already known as steroid C17,20-lyase inhibitors. Steroid-type compounds are disclosed in, for example, WO92/15404, WO93/20097, EP-A-288053, EP-A-413270 and the like. As non-steroid type compounds, for example, JP-A-64-85975 discloses (1H-imidazol-1-yl)methyl-substituted benzimidazole derivatives, WO94/27989 and WO96/14090 disclose carbazole derivatives, WO95/09157 discloses azole derivatives, U.S. Pat. No. 5,491,161 discloses 1H-benzimidazole derivatives and WO99/18075 discloses dihydronaphthalene derivatives.
Heretofore, there has not been obtained a steroid C17,20-lyase inhibitor applicable to clinical situations, and early development of a steroid C17,20-lyase inhibitor highly useful as a pharmaceutical is desired.